Cellular System Selection Frequency Scan Scope

ABSTRACT

Apparatuses, systems, and methods for user equipment (UE) devices to perform more efficient frequency scans for potential base stations. According to techniques described herein, the UE may determine that it does not have cellular service and determine first information based on a last camped cell. A time period during which the first information was acquired may be determined and one or more frequency scans may be performed. The frequency scans may be limited to a set of frequencies based in part on the time period. Thus, if the time period is less than a first value, the set of frequencies may include a first set of frequencies and if the time period is greater than the first value but less than a second value, the set of frequencies may include the first set of frequencies and a second set of frequencies.

PRIORITY DATA

This application is a continuation of U.S. patent application Ser. No.16/372,263, titled “Cellular System Selection Frequency Scan Scope”,filed Apr. 1, 2019, which claim benefit of priority to U.S. patentapplication Ser. No. 15/590,127, titled “Cellular System SelectionFrequency Scan Scope”, filed May 9, 2017, now U.S. Pat. No. 10,251,095,which claims benefit of priority to U.S. Provisional Application Ser.No. 62/380,305, titled “Cellular System Selection Frequency Scan Scope”,filed Aug. 26, 2016, each of which is hereby incorporated by referencein its entirety as though fully and completely set forth herein.

The claims in the instant application are different than those of theparent application and/or other related applications. The Applicanttherefore rescinds any disclaimer of claim scope made in the parentapplication and/or any predecessor application in relation to theinstant application. Any such previous disclaimer and the citedreferences that it was made to avoid, may need to be revisited. Further,any disclaimer made in the instant application should not be read intoor against the parent application and/or other related applications.

FIELD

The present application relates to wireless devices, and moreparticularly to an apparatus, system, and method for wireless devices toperform cellular system selection during limited service and/or forconnected mode out of service recovery.

DESCRIPTION OF THE RELATED ART

Wireless communication systems are rapidly growing in usage. Further,wireless communication technology has evolved from voice-onlycommunications to also include the transmission of data, such asInternet and multimedia content. In certain scenarios, a wireless devicemay use a search algorithm to acquire service with a wireless network.These search algorithms may burden device resources. Thus, improvementsin the field are desired.

SUMMARY

Embodiments are presented herein of methods for wireless devices to moreefficiently scan frequency bands for potential base stations and ofdevices configured to implement these methods. Embodiments relate to auser equipment (UE) device having at least one antenna for performingwireless communications, a radio, and a processing element coupled tothe radio. The UE may perform voice and/or data communications, as wellas the methods described herein.

According to the techniques described herein, the UE, or a processor ofthe UE (e.g., such as a baseband processor), may determine that the UEdoes not have cellular service and determine first information based ona last cell the UE camped on. The UE may also determine a time periodduring which the first information was acquired and perform one or morefrequency scans limited to a set of frequencies based in part on thetime period. In some embodiments, to determine the time period, the UEmay determine whether the time period is less than a first value, whereif the time period is less than the first value, the set of frequenciesmay include a first set of frequencies, where if the time period isgreater than the first value but less than a second value, the set offrequencies may include the first set of frequencies and a second set offrequencies, where if the time period is greater than the second value,the set of frequencies may include the first and second sets offrequencies and a third set of frequencies.

Further, according to the techniques described herein, the UE, or aprocessor of the UE (e.g., such as a baseband processor), may determinethat the UE does not have cellular service and determine firstinformation based on a last cell the UE was camped on. In addition, theUE may determine a time period during which the first information wasacquired and perform one or more frequency scans limited to a set offrequencies based, at least in part on the time period, wherein if thetime period is less than a first value, the set of frequencies comprisefrequencies stored on the UE in local acquisition database (ACQ-DB) suchas local and local enhanced ACQ-DBs and/or assisted local and localenhanced ACQ-DBs. In some embodiments, if the time period is less thanthe first value, the set of frequencies may include a first set offrequencies, where if the time period is greater than the first valuebut less than a second value, the set of frequencies may include thefirst set of frequencies and a second set of frequencies, where if thetime period is greater than the second value, the set of frequencies mayinclude the first and second sets of frequencies and a third set offrequencies.

In addition, according to the techniques described herein, the UE, or aprocessor of the UE (e.g., such as a baseband processor) may determinethat the UE does not have cellular service and determine whether firstinformation associated with a last cell the UE camped on was acquiredwithin a first time period. The UE may, in response to determining thatthe first information was acquired within the first time period, performone or more frequency scans limited to a first set of frequencies. Inaddition, the UE may in response to determining that the firstinformation was not acquired within the first time period, perform oneor more frequency scans limited to a second set of frequencies, wherethe first set of frequencies is a subset of the second set offrequencies. In some embodiments, the UE may determine that the firstinformation was not acquired within a second time period, where thesecond time period is greater than the first time period, and inresponse to determining that the first information was not acquiredwithin the second time period, perform one or more frequency scanslimited to a third set of frequencies, where the second set offrequencies is a subset of the third set of frequencies.

The techniques described herein may be implemented in and/or used with anumber of different types of devices, including but not limited tocellular phones, tablet computers, wearable computing devices, portablemedia players, and any of various other computing devices.

This Summary is intended to provide a brief overview of some of thesubject matter described in this document. Accordingly, it will beappreciated that the above-described features are merely examples andshould not be construed to narrow the scope or spirit of the subjectmatter described herein in any way. Other features, aspects, andadvantages of the subject matter described herein will become apparentfrom the following Detailed Description, Figures, and Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present subject matter can be obtainedwhen the following detailed description of various embodiments isconsidered in conjunction with the following drawings, in which:

FIG. 1 illustrates an example wireless communication system according tosome embodiments.

FIG. 2 illustrates an example system in which a UE can selectivelyeither directly communicate with a cellular base station or utilize thecellular capabilities of a companion or proxy device such as another UE,according to some embodiments.

FIG. 3 illustrates an example block diagram of a UE according to someembodiments;

FIG. 4 illustrates an example block diagram of a BS according to someembodiments;

FIG. 5A illustrates a state machine with multiple states representingexemplary scan scopes, according to some embodiments;

FIG. 5B illustrates scan scope relationships corresponding to thevarious states illustrated in FIG. 5A, according to some embodiments;and

FIG. 6 is a flowchart diagram illustrating a method to determine scanscope, according to some embodiments.

While the features described herein may be susceptible to variousmodifications and alternative forms, specific embodiments thereof areshown by way of example in the drawings and are herein described indetail. It should be understood, however, that the drawings and detaileddescription thereto are not intended to be limiting to the particularform disclosed, but on the contrary, the intention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the subject matter as defined by the appended claims.

DETAILED DESCRIPTION Terms

The following is a glossary of terms used in this disclosure:

Memory Medium—Any of various types of non-transitory memory devices orstorage devices. The term “memory medium” is intended to include aninstallation medium, e.g., a CD-ROM, floppy disks, or tape device; acomputer system memory or random access memory such as DRAM, DDR RAM,SRAM, EDO RAM, Rambus RAM, etc.; a non-volatile memory such as a Flash,magnetic media, e.g., a hard drive, or optical storage; registers, orother similar types of memory elements, etc. The memory medium mayinclude other types of non-transitory memory as well or combinationsthereof. In addition, the memory medium may be located in a firstcomputer system in which the programs are executed, or may be located ina second different computer system which connects to the first computersystem over a network, such as the Internet. In the latter instance, thesecond computer system may provide program instructions to the firstcomputer for execution. The term “memory medium” may include two or morememory mediums which may reside in different locations, e.g., indifferent computer systems that are connected over a network. The memorymedium may store program instructions (e.g., embodied as computerprograms) that may be executed by one or more processors.

Carrier Medium—a memory medium as described above, as well as a physicaltransmission medium, such as a bus, network, and/or other physicaltransmission medium that conveys signals such as electrical,electromagnetic, or digital signals.

Programmable Hardware Element—includes various hardware devicescomprising multiple programmable function blocks connected via aprogrammable interconnect. Examples include FPGAs (Field ProgrammableGate Arrays), PLDs (Programmable Logic Devices), FPOAs (FieldProgrammable Object Arrays), and CPLDs (Complex PLDs). The programmablefunction blocks may range from fine grained (combinatorial logic or lookup tables) to coarse grained (arithmetic logic units or processorcores). A programmable hardware element may also be referred to as“reconfigurable logic”.

Computer System—any of various types of computing or processing systems,including a personal computer system (PC), mainframe computer system,workstation, network appliance, Internet appliance, personal digitalassistant (PDA), television system, grid computing system, or otherdevice or combinations of devices. In general, the term “computersystem” can be broadly defined to encompass any device (or combinationof devices) having at least one processor that executes instructionsfrom a memory medium.

User Equipment (UE) (or “UE Device”)—any of various types of computersystems devices which are mobile or portable and which performs wirelesscommunications. Examples of UE devices include mobile telephones orsmart phones (e.g., iPhone™, Android™-based phones), portable gamingdevices (e.g., Nintendo DS™, PlayStation Portable™, Gameboy Advance™,iPhone™), laptops, wearable devices (e.g. smart watch, smart glasses),PDAs, portable Internet devices, music players, data storage devices, orother handheld devices, etc. In general, the term “UE” or “UE device”can be broadly defined to encompass any electronic, computing, and/ortelecommunications device (or combination of devices) which is easilytransported by a user and capable of wireless communication.

Base Station—The term “Base Station” has the full breadth of itsordinary meaning, and at least includes a wireless communication stationinstalled at a fixed location and used to communicate as part of awireless telephone system or radio system.

Processing Element—refers to various elements or combinations ofelements. Processing elements include, for example, circuits such as anASIC (Application Specific Integrated Circuit), portions or circuits ofindividual processor cores, entire processor cores, individualprocessors, programmable hardware devices such as a field programmablegate array (FPGA), and/or larger portions of systems that includemultiple processors.

Channel—a medium used to convey information from a sender (transmitter)to a receiver. It should be noted that since characteristics of the term“channel” may differ according to different wireless protocols, the term“channel” as used herein may be considered as being used in a mannerthat is consistent with the standard of the type of device withreference to which the term is used. In some standards, channel widthsmay be variable (e.g., depending on device capability, band conditions,etc.). For example, LTE may support scalable channel bandwidths from 1.4MHz to 20 MHz. In contrast, WLAN channels may be 22 MHz wide whileBluetooth channels may be 1 Mhz wide. Other protocols and standards mayinclude different definitions of channels. Furthermore, some standardsmay define and use multiple types of channels, e.g., different channelsfor uplink or downlink and/or different channels for different uses suchas data, control information, etc.

Band—The term “band” has the full breadth of its ordinary meaning, andat least includes a section of spectrum (e.g., radio frequency spectrum)in which channels are used or set aside for the same purpose.

Automatically—refers to an action or operation performed by a computersystem (e.g., software executed by the computer system) or device (e.g.,circuitry, programmable hardware elements, ASICs, etc.), without userinput directly specifying or performing the action or operation. Thusthe term “automatically” is in contrast to an operation being manuallyperformed or specified by the user, where the user provides input todirectly perform the operation. An automatic procedure may be initiatedby input provided by the user, but the subsequent actions that areperformed “automatically” are not specified by the user, i.e., are notperformed “manually”, where the user specifies each action to perform.For example, a user filling out an electronic form by selecting eachfield and providing input specifying information (e.g., by typinginformation, selecting check boxes, radio selections, etc.) is fillingout the form manually, even though the computer system must update theform in response to the user actions. The form may be automaticallyfilled out by the computer system where the computer system (e.g.,software executing on the computer system) analyzes the fields of theform and fills in the form without any user input specifying the answersto the fields. As indicated above, the user may invoke the automaticfilling of the form, but is not involved in the actual filling of theform (e.g., the user is not manually specifying answers to fields butrather they are being automatically completed). The presentspecification provides various examples of operations beingautomatically performed in response to actions the user has taken.

Approximately—refers to a value that is almost correct or exact. Forexample, approximately may refer to a value that is within 1 to 10percent of the exact (or desired) value. It should be noted, however,that the actual threshold value (or tolerance) may be applicationdependent. For example, in one embodiment, “approximately” may meanwithin 0.1% of some specified or desired value, while in various otherembodiments, the threshold may be, for example, 2%, 3%, 5%, and soforth, as desired or as required by the particular application.

Various components may be described as “configured to” perform a task ortasks. In such contexts, “configured to” is a broad recitation generallymeaning “having structure that” performs the task or tasks duringoperation. As such, the component can be configured to perform the taskeven when the component is not currently performing that task (e.g., aset of electrical conductors may be configured to electrically connect amodule to another module, even when the two modules are not connected).In some contexts, “configured to” may be a broad recitation of structuregenerally meaning “having circuitry that” performs the task or tasksduring operation. As such, the component can be configured to performthe task even when the component is not currently on. In general, thecircuitry that forms the structure corresponding to “configured to” mayinclude hardware circuits.

Various components may be described as performing a task or tasks, forconvenience in the description. Such descriptions should be interpretedas including the phrase “configured to.” Reciting a component that isconfigured to perform one or more tasks is expressly intended not toinvoke 35 U.S.C. § 112(f) interpretation for that component.

FIGS. 1 and 2—Communication System

FIG. 1 illustrates a simplified example wireless communication system,according to one embodiment. It is noted that the system of FIG. 1 ismerely one example of a possible system, and that features of thisdisclosure may be implemented in any of various systems, as desired.

As shown, the example wireless communication system includes a basestation 102A which communicates over a transmission medium with one ormore wireless devices 106A, 106B, etc., as well as accessory device (oraccessory UE) 107. Wireless devices 106A, 106B, and 107 may be userdevices, which may be referred to herein as “user equipment” (UE) or UEdevices.

The base station (BS) 102A may be a base transceiver station (BTS) orcell site (a “cellular base station”), and may include hardware thatenables wireless communication with wireless devices 106A, 106B, and107.

The communication area (or coverage area) of the base station may bereferred to as a “cell.” The base station 102A and the UEs 106/107 maybe configured to communicate over the transmission medium using any ofvarious radio access technologies (RATs), also referred to as wirelesscommunication technologies, or telecommunication standards, such as 5Gnew radio (5G NR), GSM, UMTS (associated with, for example, WCDMA orTD-SCDMA air interfaces), LTE, LTE-Advanced (LTE-A), HSPA, 3GPP2CDMA2000 (e.g., 1×RTT, 1×EV-DO, HRPD, eHRPD), etc. Note that if the basestation 102A is implemented in the context of LTE, it may alternately bereferred to as an ‘eNodeB’.

As shown, the base station 102A may also be equipped to communicate witha network 100 (e.g., a core network of a cellular service provider, atelecommunication network such as a public switched telephone network(PSTN), and/or the Internet, among various possibilities). Thus, thebase station 102A may facilitate communication between the user devicesand/or between the user devices and the network 100. In particular, thecellular base station 102A may provide UEs 106/107 with varioustelecommunication capabilities, such as voice, SMS and/or data services.

Base station 102A and other similar base stations (such as base stations102B . . . 102N) operating according to the same or a different cellularcommunication standard may thus be provided as a network of cells, whichmay provide continuous or nearly continuous overlapping service to UEs106/107 and similar devices over a wide geographic area via one or morecellular communication standards.

Thus, while base station 102A may act as a “serving cell” for UEs106/107 as illustrated in FIG. 1, each UE 106/107 may also be capable ofreceiving signals from (and possibly within communication range of) oneor more other cells (which might be provided by base stations 102B-Nand/or any other base stations), which may be referred to as“neighboring cells”. Such cells may also be capable of facilitatingcommunication between user devices and/or between user devices and thenetwork 100. Such cells may include “macro” cells, “micro” cells, “pico”cells, and/or cells which provide any of various other granularities ofservice area size. For example, base stations 102A-B illustrated in FIG.1 might be macro cells, while base station 102N might be a micro cell.Other configurations are also possible.

Note that a UE 106/107 may be capable of communicating using multiplewireless communication standards. For example, UE 106/107 may beconfigured to communicate using a wireless networking (e.g., Wi-Fi)and/or peer-to-peer wireless communication protocol (e.g., Bluetooth,Wi-Fi peer-to-peer, etc.) in addition to at least one cellularcommunication protocol (e.g., GSM, UMTS (associated with, for example,WCDMA or TD-SCDMA air interfaces), 5G NR, LTE, LTE-A, HSPA, 3GPP2CDMA2000 (e.g., 1×RTT, 1×EV-DO, HRPD, eHRPD), etc.). UE 106/107 may alsoor alternatively be configured to communicate using one or more globalnavigational satellite systems (GNSS, e.g., GPS or GLONASS), one or moremobile television broadcasting standards (e.g., ATSC-M/H or DVB-H),and/or any other wireless communication protocol, if desired. Othercombinations of wireless communication standards (including more thantwo wireless communication standards) are also possible.

The UEs 106A and 106B are typically handheld devices such as smartphones or tablets, but may be any of various types of device withcommunication capability, such as cellular communications capability.The UE 106B may be configured to communicate with the UE device 107,which may be referred to as an accessory device 107. The accessorydevice 107 may be any of various types of devices, typically a wearabledevice that has a smaller form factor, and may have limited battery,output power and/or communications abilities relative to UEs 106. Inother words, accessory device 107 may be referred to as a lower powerdevice whereas UE 106 may be referred to as a higher power device. Asone common example, the UE 106B may be a smart phone carried by a user,and the accessory device 107 may be a smart watch worn by that sameuser, or possibly a different user. Thus, as another example, the UE106B may be a smart phone carried by a first user, and the accessorydevice 107 may be a smart watch worn by a second, different user. The UE106B and the accessory device 107 may communicate using any of variousshort-range communication protocols, such as Bluetooth, Wi-Fi, etc.

The accessory device 107 includes communications capability, e.g.,cellular communication capability, and hence is able to directlycommunicate with cellular base station 102. However, since the accessorydevice 107 is possibly limited in one or more of its communicationcapabilities, output power, and/or battery, the accessory device 107 mayin some instances selectively utilize the UE 106B as a proxy forcommunication purposes with the base station 102 and hence to thenetwork 100. In other words, the accessory device 107 may selectivelyuse the cellular communication capabilities of the UE 106B to conductits cellular communications. The limitation on communication abilitiesof the accessory device 107 can be permanent, e.g., due to limitationsin output power or the radio access technologies (RATs) supported, ortemporary, e.g., due to conditions such as current battery status,inability to access a network, or poor reception.

FIG. 2—Example System with Accessory Device

FIG. 2 illustrates an example accessory device 107 in communication withbase station 102. The accessory device 107 may be a wearable device suchas a smart watch or band. The accessory device 107 may comprise cellularcommunication capability and be capable of directly communicating withthe base station 102 as shown. When the accessory device 107 isconfigured to directly communicate with the base station, the accessorydevice may be said to be in “autonomous mode.”

The accessory device 107 may also be capable of communicating withanother device (e.g., UE 106), referred to as a proxy device orintermediate device, using a short-range communications protocol, andmay then use the cellular functionality of this proxy device forcommunicating cellular voice/data with the base station 102. In otherwords, the accessory device 107 may provide voice/data packets intendedfor the base station 102 over the short-range link to the UE 106, andthe UE 106 may use its cellular functionality to transmit (or relay)this voice/data to the base station on behalf of the accessory device107. Similarly, the voice/data packets transmitted by the base stationand intended for the accessory device 107 may be received by thecellular functionality of the UE 106 and then may be relayed over theshort-range link to the accessory device. As noted above, the UE 106 maybe a mobile phone, a tablet, or any other type of hand-held device, amedia player, a computer, a laptop or virtually any type of wirelessdevice. When the accessory device 107 is configured to indirectlycommunicate with the base station using the cellular functionality of anintermediate or proxy device, the accessory device may be said to be in“relay mode.”

The various embodiments herein are described with respect to theaccessory device 107 selectively using either its own cellularfunctionality (autonomous mode) to communicate with a base station, orusing the cellular functionality of the UE 106 (relay mode) forcommunications, e.g., for LTE or VoLTE. However, embodiments describedherein may also be used with other radio access technologies (RATs),such as to enable the accessory device 107 to selectively using eitherits own Wi-Fi functionality (autonomous mode) to communicate with aWi-Fi access point, or use the Wi-Fi functionality of the UE 106 (relaymode) for Wi-Fi communications.

The accessory device 107 may include a processor that is configured toexecute program instructions stored in memory. The accessory device 107may perform any of the method embodiments described herein by executingsuch stored instructions. Alternatively, or in addition, the accessorydevice 107 may include a processing element, such as a programmablehardware element such as an FPGA (field-programmable gate array),integrated circuit (IC), or other circuitry, that is configured toperform any of the method embodiments described herein, or any portionof any of the method embodiments described herein.

The accessory device 107 may include one or more antennas forcommunicating using two or more wireless communication protocols orradio access technologies. In some embodiments, the UE device 106 mightbe configured to communicate using a single shared radio. The sharedradio may couple to a single antenna, or may couple to multiple antennas(e.g., for MIMO) for performing wireless communications. Alternatively,the UE device 106 may include two or more radios. For example, the UE106 might include a shared radio for communicating using either of 5GNR, LTE (or LTE-Advanced) or Bluetooth, and separate radios forcommunicating using each of 5G NR, LTE-Advanced and Bluetooth. Otherconfigurations are also possible.

The accessory device 107 may be any of various types of devices that, insome embodiments, has a smaller form factor relative to a conventionalsmart phone, and may have one or more of limited communicationcapabilities, limited output power, or limited battery life relative toa conventional smart phone, e.g., accessory device 107 may be a lowerpower device or link budget limited device. As noted above, in someembodiments, the accessory device 107 is a smart watch or other type ofwearable device. As another example, the accessory device 107 may be atablet device, such as an iPad, with Wi-Fi capabilities (and possiblylimited or no cellular communication capabilities) that is not currentlynear a Wi-Fi hotspot and hence is not currently able to communicate overWi-Fi with the Internet. Thus, the term “accessory device” refers to anyof various types of devices that in some instances have limited orreduced communication capabilities and hence may selectively andopportunistically utilize the UE 106 as a proxy for communicationpurposes for one or more applications and/or RATs. When the UE 106 iscapable of being used by the accessory device 107 as a proxy, the UE 106may be referred to as a companion device to the accessory device 107.

FIG. 3—Block Diagram of a UE

FIG. 3 illustrates an example block diagram of a UE 107, according tosome embodiments. As shown, the UE 107, which may be an accessory deviceas described above, may include a system on chip (SOC) 300, which mayinclude portions for various purposes. For example, as shown, the SOC300 may include processor(s) 302 which may execute program instructionsfor the UE 106 and display circuitry 304 which may perform graphicsprocessing and provide display signals to the display 360. Theprocessor(s) 302 may also be coupled to memory management unit (MMU)340, which may be configured to receive addresses from the processor(s)302 and translate those addresses to locations in memory (e.g., memory306, read only memory (ROM) 350, NAND flash memory 310) and/or to othercircuits or devices, such as the display circuitry 304, wirelesscommunication circuitry 330, connector I/F 320, and/or display 360. TheMMU 340 may be configured to perform memory protection and page tabletranslation or set up. In some embodiments, the MMU 340 may be includedas a portion of the processor(s) 302.

As shown, the SOC 300 may be coupled to various other circuits of the UE107. For example, the UE 107 may include various types of memory (e.g.,including NAND flash 310), a connector interface 320 (e.g., for couplingto a computer system, dock, charging station, etc.), the display 360,and wireless communication circuitry 330 (e.g., for 5G NR, LTE, LTE-A,CDMA2000, Bluetooth, Wi-Fi, GPS, etc.).

As shown, the UE device 107 may include at least one antenna (andpossibly multiple antennas, e.g., for MIMO and/or for implementingdifferent wireless communication technologies, among variouspossibilities) for performing wireless communication with base stations,access points, and/or other devices. For example, the UE device 107 mayuse antenna 335 to perform the wireless communication.

The UE 107 may also include and/or be configured for use with one ormore user interface elements. The user interface elements may includeany of various elements, such as display 360 (which may be a touchscreendisplay), a keyboard (which may be a discrete keyboard or may beimplemented as part of a touchscreen display), a mouse, a microphoneand/or speakers, one or more cameras, one or more buttons, and/or any ofvarious other elements capable of providing information to a user and/orreceiving or interpreting user input.

As described herein, the UE 107 may include hardware and softwarecomponents for implementing methods according to embodiments of thisdisclosure. The processor 302 of the UE device 107 may be configured toimplement part or all of the methods described herein, e.g., byexecuting program instructions stored on a memory medium (e.g., anon-transitory computer-readable memory medium). In other embodiments,processor 302 may be configured as a programmable hardware element, suchas an FPGA (Field Programmable Gate Array), or as an ASIC (ApplicationSpecific Integrated Circuit). Alternatively (or in addition) theprocessor 302 of the UE device 107, in conjunction with one or more ofthe other components 300, 304, 306, 310, 320, 330, 335, 340, 350, 360may be configured to implement part or all of the features describedherein, such as the features described herein.

FIG. 4—Block Diagram of a Base Station

FIG. 4 illustrates an example block diagram of a base station 102,according to one embodiment. It is noted that the base station of FIG. 4is merely one example of a possible base station. As shown, the basestation 102 may include processor(s) 404 which may execute programinstructions for the base station 102. The processor(s) 404 may also becoupled to memory management unit (MMU) 440, which may be configured toreceive addresses from the processor(s) 404 and translate thoseaddresses to locations in memory (e.g., memory 460 and read only memory(ROM) 450) or to other circuits or devices.

The base station 102 may include at least one network port 470. Thenetwork port 470 may be configured to couple to a telephone network andprovide a plurality of devices, such as UE devices 106/107, access tothe telephone network as described above in FIGS. 1 and 2.

The network port 470 (or an additional network port) may also oralternatively be configured to couple to a cellular network, e.g., acore network of a cellular service provider. The core network mayprovide mobility related services and/or other services to a pluralityof devices, such as UE devices 106/107. In some cases, the network port470 may couple to a telephone network via the core network, and/or thecore network may provide a telephone network (e.g., among other UEdevices serviced by the cellular service provider).

The base station 102 may include at least one antenna 434, and possiblymultiple antennas. The at least one antenna 434 may be configured tooperate as a wireless transceiver and may be further configured tocommunicate with UE devices 106 via radio 430. The antenna 434communicates with the radio 430 via communication chain 432.Communication chain 432 may be a receive chain, a transmit chain orboth. The radio 430 may be configured to communicate via variouswireless communication standards, including, but not limited to, 5G NR,LTE, LTE-A, GSM, UMTS, CDMA2000, Wi-Fi, etc.

The base station 102 may be configured to communicate wirelessly usingmultiple wireless communication standards. In some instances, the basestation 102 may include multiple radios, which may enable the basestation 102 to communicate according to multiple wireless communicationtechnologies. For example, as one possibility, the base station 102 mayinclude an LTE/5G NR radio for performing communication according toLTE/5G NR as well as a Wi-Fi radio for performing communicationaccording to Wi-Fi. In such a case, the base station 102 may be capableof operating as both an LTE/5G NR base station and a Wi-Fi access point.As another possibility, the base station 102 may include a multi-moderadio which is capable of performing communications according to any ofmultiple wireless communication technologies (e.g., 5G NR and Wi-Fi, LTEand Wi-Fi, LTE and UMTS, LTE and CDMA2000, UMTS and GSM, etc.).

As described further subsequently herein, the BS 102 may includehardware and software components for implementing or supportingimplementation of features described herein. The processor 404 of thebase station 102 may be configured to implement or supportimplementation of part or all of the methods described herein, e.g., byexecuting program instructions stored on a memory medium (e.g., anon-transitory computer-readable memory medium). Alternatively, theprocessor 404 may be configured as a programmable hardware element, suchas an FPGA (Field Programmable Gate Array), or as an ASIC (ApplicationSpecific Integrated Circuit), or a combination thereof. Alternatively(or in addition) the processor 404 of the BS 102, in conjunction withone or more of the other components 430, 432, 434, 440, 450, 460, 470may be configured to implement or support implementation of part or allof the features described herein.

Cellular System Selection

In some existing implementations, lower power (link budget limited, oraccessory) devices, e.g., such as small form factor UEs and/or wearabledevices, may not be serviceable by cellular systems deployed based onhigher power devices, e.g., standard sized or higher power UEs such asan iPhone or iPad. In other words, devices with RF impairmentlimitations (e.g., due to form factor and/or available power) may nothave service at cell edges in existing deployments which are based onhigher powered devices (e.g., devices without an RF impairment due toform factor and/or available power). In such implementations, lowerpower devices (e.g., accessory devices) may frequently lose cellularservice which may trigger frequent system scans to recover the lostcellular service. At cell edges, powering on such lower power devicesmay also cause aggressive system scans to discover service leading to areduction in battery charge.

In some existing implementations, a lower power (accessory) device mayaccess various databases to determine available frequencies that theaccessory device may scan to attempt to acquire service. For example,the lower power device may have access to a local acquisition database(ACQ-DB) containing a history of recently acquired systems andcorresponding frequencies. The lower power device may also have accessto a local enhanced acquisition database (EACQ-DB) containing neighborfrequencies received in a system information block (SIB) from recentlyacquired systems. In addition, a lower power device may have access tosimilar databases shared by a companion device (or companion UE), suchas an assisted ACQ-DB (containing recently used ACQ-DB received from thecompanion device) or an assisted EACQ-DB (containing neighborfrequencies received in a SIB by the companion device and received fromthe companion device).

Further, the lower power device may have access to databases based onthe location (e.g., location assisted databases) of the lower powerdevice, including information identifying frequencies on which cells maybe deployed. For example, a first database (e.g., LOC-ASSIST-DB-R1) mayinclude all frequencies corresponding to a first radius (e.g., 25kilometers) about the location of the lower power device and a seconddatabase (e.g., LOC-ASSIST-DB-R2) may include all frequenciescorresponding to a second radius (e.g., 50 kilometers) about thelocation of the lower power device. Note that radii of 25 kilometers and50 kilometers are merely exemplary, and other radii are contemplated,e.g., 10 kilometers and 20 kilometers, 20 kilometers and 30 kilometers,30 kilometers and 50 kilometers, and so forth.

In addition, the lower power device may also have access to a publicland mobile network (PLMN) database that includes all deployedfrequencies for the PLMN by a cellular operator. Thus, the lower powerdevice may have a wide range of frequencies that are available forscanning, however, due to limited power resources, scanning allavailable frequencies may not be practical and/or possible. In addition,due to power restrictions/limitations, not all frequencies deployed maybe useable by the lower power device.

Embodiments describe herein relate to techniques for regaining servicevia initial selection of a limited scan scope and progressively limitingscan scope as information regarding available frequencies is obtained.

Scan Scope

In some embodiments, scan scope may be based, at least in part, onprevious camped information and a timeliness of the previous campedinformation. In other words, a scope of frequencies to be scanned toacquire and/or re-acquire service may be based on information obtainedfrom a most recent cell (or cellular system/PLMN) a device (e.g., suchas UEs 106 and 107 described above) was camped on, e.g., if theinformation was acquired within a specified time frame, e.g., within 2hours, 3 hours, 4 hours, 8 hours, and so forth.

For example, if the device has last camped cell identifier (ID)information that was acquired within a recent time frame, e.g., theinformation is less than two hours old (note that two hours is merely anexample, and other time frames are contemplated, e.g., less than 15minutes, less than 30 minutes, less than 45 minutes, less than 1 hour,less than 1.5 hours, less than 3 hours, less than 4 hours, and soforth), the device may limit an initial scan scope to local and assistedACQ-DBs and EACQ-DBs and location assisted databases, e.g., a firstdatabase (e.g., LOC-ASSIST-DB-R1) corresponding to a first radius aboutthe location of the device and a second database (e.g.,LOC-ASSIST-DB-R2) corresponding to second radius about the location ofthe device. In other words, the device may limit an initial scan scopeto recently acquired systems and corresponding frequencies and neighborcell frequencies based on local databases and databases shared by acompanion UE as well as cell frequencies based on location baseddatabases. In some embodiments, the device may not perform band scans byassuming that the device is still within a boundary of the last campedcell and may further assume that an RF impairment caused the loss ofcellular service. In some embodiments, the device may prioritize homePLMN frequencies for scanning followed by frequencies found in a firstlocation assisted database (e.g., LOC-ASSIST-DB-R1), ACQ-DB frequencies,EACQ-DB frequencies, and then frequencies found in a second locationassisted database (e.g., LOC-ASSIST-DB-R2) encompassing a larger regionthan the first location assisted database.

As another example, if the device has last camped cell ID informationthat was acquired within a less recent time frame, e.g., the informationis more than three hours old (note that three hours is merely anexample, and other time frames are contemplated, e.g., more than 15minutes, more than 30 minutes, more than 45 minutes, more than 1 hour,more than 1.5 hours, more than 2 hours, more than 4 hours, and soforth), the device may limit the initial scan scope to local ACQ-DB andEACQ-DB as well as PLMN-DB. In other words, the device may limit aninitial scan scope to recently acquired systems and correspondingfrequencies and neighbor cell frequencies based on local databases aswell as cell frequencies based on location based databases and PLMNdatabase (DB) frequencies corresponding to preferred PLMN's (PPLMN)frequencies of the last known country. In some embodiments, the devicemay not perform band scans by assuming that the device is still within aboundary of the last camped cell and may further assume that an RFimpairment caused the loss of cellular service. In some embodiments, thedevice may prioritize home PLMN (HPLMN) frequencies for scanningfollowed by frequencies found in a first location assisted database(e.g., LOC-ASSIST-DB-R1, ACQ-DB, EACQ-DB), a second location assisteddatabase (e.g., LOC-ASSIST-DB-R2) encompassing a larger region than thefirst location assisted database, and PLMN-DB frequencies correspondingto PPLMN's frequencies. In some embodiments, once the device discovers acell (e.g., has a known cell ID information that was acquired within therecent time frame), the device may refresh location assisted databasesand redefine scan scope accordingly, e.g., the device may limit the scanscope to local and assisted ACQ-DBs and EACQ-DBs and location assisteddatabases, e.g., LOC-ASSIST-DB-R1 and LOC-ASSIST-DB-R2.

In yet another example, if the device has last camped cell ID that wasnot acquired recent time frame, e.g., the information is more than eighthours old (note that eight hours is merely an example, and other timeframes are contemplated, e.g., more than 1 hour, more than 2 hours, morethan 3 hours, more than 4 hours, more than 5 hours, more than 6 hours,more than 7 hours, more than 9 hours, more than 10 hours, more than 11hours, more than half a day, more than a day, and so forth), or if thedevice has no prior knowledge of location, the device may expand aninitial scan scope to ACQ-DB and EACQ-DB, LOC-ASSIST-DB-R1,LOC-ASSIST-DB-R2, PLMN-DB (HPLMN/PPLMN) frequencies based on theinformation (if any), followed by band scan on preferred RAT/bandcombinations followed by band scan on other RAT's. In some embodiments,the device may not perform band scans by assuming that the device isstill within a boundary of the last camped cell and may further assumethat an RF impairment caused the loss of cellular service. In someembodiments, the device may prioritize the HPLMN frequencies followed byfrequencies in the order of LOC-ASSIST-DB-R1, ACQ-DB and EACQ-DB,LOC-ASSIST-DB-R2, and PLMN-DB. In addition, the device may prioritizeband scan on widely deployed RAT/band combinations. In some embodiments,once the device discovers a cell (e.g., has a known cell ID informationthat was acquired within the recent time frame), the device may refreshdatabases (e.g., location assisted databases) and redefine scan scopeaccordingly, e.g., the device may limit the scan scope to local andassisted ACQ-DBs and EACQ-DBs and location assisted databases, e.g.,LOC-ASSIST-DB-R1 and LOC-ASSIST-DB-R2.

In some embodiments, the device may prefer a most recent ACQ-DB amonglocal ACQ-DB and assisted ACQ-DB. In addition, the device may prefer amost recent EACQ-DB among local EACQ-DB and assisted EACQ-DB. In otherwords, the device may prefer a database provided from a companion deviceif the database has a more recent timestamp than a corresponding localdatabase.

In some embodiments, if a device is in (or remains in) a continuous “Noservice” state, the device may change the initial scan scope by movingfrom a first state that assumes a known cell ID (e.g., last camped cellidentifier (ID) information was acquired within a recent time frame), toa second state that assumes a known country (e.g., last camped cell IDinformation was acquired within a less recent time frame), to a thirdstate that assumes an unknown location (e.g., last camped cell IDinformation was not acquired within a recent time frame). In someembodiments, transitioning from the first state to the second state andfrom the second state to the third state may be based (or triggered by)a change in device motion state. In some embodiments, transitioning fromthe first state to the second state and from the second state to thethird state may be based (or triggered by) a duration of time spent inan out of service condition. Note that the duration of time may be bothvariable (e.g., duration required to transition from first state tosecond state may be independent of, and different from, the durationrequired to transition from the second state to the third state) andconfigurable.

In some embodiments, for each scan attempt, a device may prioritize scanfrequencies based on one or more criteria. For example, a device mayprioritize a more recently refreshed database over a less recentlyrefreshed database (e.g., prioritize a local ACQ-DB over an assistedACQ-DB if a timestamp of the local ACQ-DB is more recent than atimestamp of the assisted ACQ-DB). As another example, a device mayprioritize frequencies in a first location assisted database overfrequencies in a second location assisted database where the secondlocation assisted database includes a larger region about the device ascompared to the first location assisted database. In some embodiments, adevice may utilize an ordered priority list, such as prioritizingfrequencies in the order of registered PLMN (RPLMN)/equivalent PLMN(ePLMN) lists, HPLMN/equivalent HPLMN (eHPLMN) lists, preferred PLMNs,other PLMN's excluding forbidden PLMNs (FPLMNs), and FPLMN list. In someembodiments, a device may prefer coverage band frequencies based on thelocation. In addition, a device may remove duplicate entries found onmultiple PLMN lists. In some embodiments, a device may include mostfavorable frequencies in each scan. In some embodiments, a device mayscan through all the identified frequencies through an algorithm(configurable), e.g., priority based, round robin, random, and so forth.In some instances, e.g., in complete out of coverage instances, a devicemay limit a number of frequencies for each scan attempt to aconfigurable number (e.g., 5, 10, 15, 20, and so forth to estimate powercost prior to attempting a full scan of available frequencies.

In some embodiments, a device may prioritize scans to recover serviceand to limit scan scope, e.g., attempt to find any cell. For example, asillustrated in FIGS. 5A and 5B, a device may attempt to move from acondition (or state) of unknown location to a known cell ID in order tolimit scan scope. In particular, FIG. 5A illustrates a state machinewith multiple states representing exemplary scan scopes, according tosome embodiments. FIG. 5B illustrates scan scopes relationshipscorresponding to the various states illustrated in FIG. 5A, according tosome embodiments.

As show, a device may start in, or assume, an initial state 502 (knowncell ID) corresponding to an initial scan scope as illustrated in FIG.5B. If the device determines that the last camped (e.g., last known)cell ID is not very recent (e.g., is greater than x minutes old), thenthe device may transition to state 504 (known country) corresponding toan expanded scan scope as illustrated in FIG. 5B. If the devicedetermines that the last camped cell ID is not recent (e.g., is greaterthan y minutes old where y is greater than x), the device may transitionto state 506 (un-known country) corresponding to a further expanded scanscope as illustrated in FIG. 5B. However, if the device finds (orobtains) a cell ID, the device may transition back to state 502 fromeither state 504 or 506. In other words, once the device has a recentcell ID, the device may limit scanning to the scope corresponding tostate 502.

In some embodiments, when a device is in a connected mode but out ofservice (COOS), the device may limit scan scope to frequencies fromACQ-DB (local and/or shared, if available) and eACQ-DB (local andshared) as well as location assisted databases. In addition, the devicemay filter frequencies that correspond to a last registered PLMN and itscorresponding ePLMN. In other words, the device may limit scans tofrequencies that correspond to the last registered PLMN and itscorresponding ePLMN. In some embodiments, the device may not scan forother PLMN frequencies as cellular network cannot recover the previousradio connection with non-roaming partner's networks. In someembodiments, the device may introduce a telescoping gap between eachscan attempt while maintaining a previous radio connection context. Inother words, the device may increase and/or decrease a time between scanattempts for frequencies while maintaining the previous radio connectioncontext. In some embodiments, the time between scan attempts may bebased, at least in part, on a motion state (current or averaged over atime period) of the device.

In some embodiments, when a device is camped on (e.g., connected to)limited service on a visiting PLMN (VPLMN), the device may perform asystem scan by limiting limit scan scope to frequencies from ACQ-DB(local and/or shared, if available) and eACQ-DB (local and shared) aswell as location assisted databases. In addition, the device may filterfrequencies that correspond to HPLMN/eHPLMN/PPLMN (e.g., PLMNs whichprovide normal (not limited) service). In other words, the device maylimit scans to frequencies that correspond to HPLMN, eHPLMN, and/orPPLMN. In some embodiments, the device may introduce a telescoping gapbetween each scan attempt while maintaining a previous radio connectioncontext. In other words, the device may increase and/or decrease a timebetween scan attempts for frequencies. In some embodiments, the timebetween scan attempts may be based, at least in part, on a motion state(current or averaged over a time period) of the device.

In some embodiments, when a device is camped on (e.g., connected to) aVPLMN, the device may perform a HP-PLMN scan by limiting a scan scope tothe frequencies from the databases ACQ-DB and its neighbors, andlocation assisted databases. In addition, the device may filterfrequencies from ACQ-DB (local and/or shared, if available) and eACQ-DB(local and shared) as well as the location assisted databases. Inaddition, the device may filter frequencies that correspond toHPLMN/eHPLMN/PPLMN. In some embodiments, the device may introduce atelescoping gap between each scan attempt while maintaining a previousradio connection context. In other words, the device may increase and/ordecrease a time between scan attempts for frequencies. In someembodiments, the time between scan attempts may be based, at least inpart, on a motion state (current or averaged over a time period) of thedevice.

Note that although the embodiments described herein have been describedin reference to a lower power device (e.g., an accessory device), theembodiments may be implemented on any type of device. In other words,the embodiments described herein are not limited to lower power devicesand may be implemented on standard form factor devices as describedabove.

FIG. 6—Flowchart Diagram

FIG. 6 is a flowchart diagram illustrating a method to determine scanscope, according to some embodiments. The method shown in FIG. 6 may beused in conjunction with any of the systems or devices shown in theabove Figures, among other devices. In addition, the method shown inFIG. 6 may be used in conjunction with any of the embodiments and/ortechniques described above. In various embodiments, some of the methodelements shown may be performed concurrently, in a different order thanshown, or may be omitted. Additional method elements may also beperformed as desired. As shown, this method may operate as follows.

At 602, the UE (e.g., UE 107 or UE 106) may determine that the UE doesnot have cellular service. The lack of cellular may be due to variousconditions as described above.

At 604, the UE may determine first information based, at least in part,on a last cell the UE camped on. In some embodiments, the firstinformation may be a cell ID as described above.

At 606, the UE may determine a time period during which the firstinformation was acquired. In other words, the UE may determine howrecent the first information is, e.g., whether it was acquired within afirst, second, or third time period. For example, the UE may determinewhether the first information was acquired within 1 hour, 4 hours, or 8hours of a current time. Note that these values are exemplary only, andother values/time periods (e.g., as described above) are contemplated.

At 608, the UE may perform one or more frequency scans limited to a setof frequencies based in part on the time period. In some embodiments,the set of frequencies may include frequencies stored on the UE in alocal acquisition database (ACQ-DB) and/or a local enhanced ACQ-DB aswell as a local assisted ACQ-DB or local assisted enhanced ACQ-DB. Insome embodiments, the set of frequencies may include frequencies storedin location assisted databases. In some embodiments, to perform the oneor more frequency scans, the UE is may scan frequencies stored in afirst database associated with a first time stamp prior to scanningfrequencies stored in a second database associated with a second timestamp, where the first time stamp is more recent than the second timestamp. In some embodiments, the UE may increase a time period betweenthe one or more frequency scans based, at least in part on a mobilitystate of the UE.

In some embodiments, to determine the time period, the UE may determinewhether the time period is less than a first value. In such embodiments,if the time period is less than the first value, the set of frequenciesmay include a first set of frequencies. In addition, if the time periodis greater than the first value but less than a second value, the set offrequencies may include the first set of frequencies and a second set offrequencies and if the time period is greater than the second value, theset of frequencies may include the first and second sets of frequenciesand a third set of frequencies.

In some embodiments, the UE may receive a system information block (SIB)from the last cell and the SIB may contain neighbor cell frequencies.The UE may store the neighbor cell frequencies in a local enhancedACQ-DB and the set of frequencies may include frequencies stored in thelocal enhanced ACQ-DB.

In some embodiments, the UE may receive, from a companion UE (e.g., vialocal connection such as a Bluetooth, Wi-Fi, or other peer-to-peerconnection), a local assisted ACQ-DB and the set of frequencies mayinclude frequencies stored on the UE in the local assisted ACQ-DB.

Embodiments of the present disclosure may be realized in any of variousforms. For example some embodiments may be realized as acomputer-implemented method, a computer-readable memory medium, or acomputer system. Other embodiments may be realized using one or morecustom-designed hardware devices such as ASICs. Other embodiments may berealized using one or more programmable hardware elements such as FPGAs.

In some embodiments, a non-transitory computer-readable memory mediummay be configured so that it stores program instructions and/or data,where the program instructions, if executed by a computer system, causethe computer system to perform a method, e.g., any of a methodembodiments described herein, or, any combination of the methodembodiments described herein, or, any subset of any of the methodembodiments described herein, or, any combination of such subsets.

In some embodiments, a wireless device (or wireless station) may beconfigured to include a processor (or a set of processors) and a memorymedium, where the memory medium stores program instructions, where theprocessor is configured to read and execute the program instructionsfrom the memory medium, where the program instructions are executable tocause the wireless device to implement any of the various methodembodiments described herein (or, any combination of the methodembodiments described herein, or, any subset of any of the methodembodiments described herein, or, any combination of such subsets). Thedevice may be realized in any of various forms.

Although the embodiments above have been described in considerabledetail, numerous variations and modifications will become apparent tothose skilled in the art once the above disclosure is fully appreciated.It is intended that the following claims be interpreted to embrace allsuch variations and modifications.

What is claimed is:
 1. A user equipment (UE) device, comprising: atleast one antenna for performing wireless communications; a radiocoupled to the at least one antenna; and a processing element coupled tothe radio; wherein the processing element is configured to cause the UEto: perform one or more frequency scans limited to a first set offrequencies based on determining that first information associated witha last cell the UE camped on was acquired within a first time period;and perform one or more frequency scans limited to a second set offrequencies based on determining that the first information was notacquired within the first time period, wherein the first set offrequencies is a subset of the second set of frequencies.
 2. The UE ofclaim 1, wherein the first set of frequencies include frequencies storedin one or more of a local acquisition database (ACQ-DB), a localenhanced ACQ-DB, or a location assisted database.
 3. The UE of claim 1,wherein the first set of frequencies is limited to frequenciescorresponding to a home public land mobile network (PLMN), equivalentsof the home PLMN, and a provider preferred PLMN.
 4. The UE of claim 1,wherein the first set of frequencies include frequencies correspondingto the last cell.
 5. The UE of claim 4, wherein the frequenciescorresponding to the last cell include frequencies of a last registeredpublic land mobile network (RPLMN) database.
 6. The UE of claim 1,wherein the processing element is further configured to cause the UE to:determine that the UE is camped on a visiting public land mobile network(VPLMN).
 7. The UE of claim 1, wherein the processing element is furtherconfigured to cause the UE to: determine that the first information wasnot acquired within a second time period, wherein the second time periodis greater than the first time period; and in response to determiningthat the first information was not acquired within the second timeperiod, perform one or more frequency scans limited to a third set offrequencies, wherein the second set of frequencies is a subset of thethird set of frequencies.
 8. The UE of claim 1, wherein in theprocessing element is further configured to cause the UE to: receive asystem information block from the last cell, wherein the systeminformation block contains neighbor cell frequencies; and store theneighbor cell frequencies in a local enhanced acquisition database(ACQ-DB); and wherein the second set of frequencies include frequenciesstored in the local enhanced ACQ-DB.
 9. The UE of claim 1, wherein theprocessing element is further configured to cause the UE to: receive,from a companion UE, a local assisted acquisition database (ACQ-DB),wherein the second set of frequencies include frequencies stored on theUE in the local assisted ACQ-DB.
 10. A non-transitory computeraccessible memory medium comprising program instructions which, whenexecuted at a wireless user equipment (UE) device, cause the UE to:perform one or more frequency scans limited to a first set offrequencies based on determining that first information associated witha last cell the UE camped on was acquired within a first time period;and perform one or more frequency scans limited to a second set offrequencies based on determining that the first information was notacquired within the first time period, wherein the first set offrequencies is a subset of the second set of frequencies.
 11. Thenon-transitory computer accessible memory medium of claim 10, whereinthe first set of frequencies include frequencies stored in one or moreof a local acquisition database (ACQ-DB), a local enhanced ACQ-DB, or alocation assisted database.
 12. The non-transitory computer accessiblememory medium of claim 10, wherein the first set of frequencies islimited to frequencies corresponding to a home public land mobilenetwork (PLMN), equivalents of the home PLMN, and a provider preferredPLMN.
 13. The non-transitory computer accessible memory medium of claim10, wherein the first set of frequencies include frequenciescorresponding to the last cell.
 14. The non-transitory computeraccessible memory medium of claim 10, wherein the second set offrequencies include frequencies stored in location assisted databasesstored on the UE.
 15. The non-transitory computer accessible memorymedium of claim 10, wherein the frequencies corresponding to the lastcell include frequencies of a last registered public land mobile network(RPLMN) database.
 16. An apparatus, comprising: a memory; and aprocessing element in communication with the memory, wherein theprocessing element is configured to: perform one or more frequency scanslimited to a first set of frequencies based on determining that firstinformation associated with a last cell a user equipment device (UE)camped on was acquired within a first time period; and perform one ormore frequency scans limited to a second set of frequencies based ondetermining that the first information was not acquired within the firsttime period, wherein the first set of frequencies is a subset of thesecond set of frequencies.
 17. The apparatus of claim 16, wherein thefirst set of frequencies include frequencies stored in one or more of alocal acquisition database (ACQ-DB), a local enhanced ACQ-DB, or alocation assisted database.
 18. The apparatus of claim 16, wherein thefirst set of frequencies is limited to frequencies corresponding to ahome public land mobile network (PLMN), equivalents of the home PLMN,and a provider preferred PLMN.
 19. The apparatus of claim 16, whereinthe first set of frequencies include frequencies corresponding to thelast cell.
 20. The apparatus of claim 16, wherein the second set offrequencies include frequencies stored in location assisted databasesstored on the UE.